Search for the B→Y(4260)K, Y(4260)→J/ψπ+π− decays

Abstract

We report the results of a search for the B→Y(4260)K, Y(4260)→J/ψπ+π− decays. This study is based on a data sample corresponding to an integrated luminosity of 711 fb−1, collected at the Υ(4S) resonance with the Belle detector at the KEKB asymmetric-energy e+e− collider. We investigate the J/ψπ+π− invariant mass distribution in the range 4.0 to 4.6 GeV/c2 using both B+→J/ψπ+π−K+ and B0→J/ψπ+π−K0S decays. We find excesses of events above the background levels, with significances of 2.1 and 0.9 standard deviations for charged and neutral B→Y(4260)K decays, respectively, taking into account the systematic uncertainties. These correspond to upper limits on the product of branching fractions, B(B+→Y(4260)K+)×B(Y(4260)→J/ψπ+π−)<1.4×10−5 and B(B0→Y(4260)K0)×B(Y(4260)→J/ψπ+π−)<1.7×10−5 at the 90% confidence level.